The need for reducing the weight of ships is well known. A major weight component of propeller-driven ships is the reduction gear mechanism. The reduction gear is also associated with high costs of production and maintenance. U.S. Pat. Nos. 1,805,597 and 2,298,869 are directed to ship propulsion systems in which the reduction gear is eliminated and power for the propellers is generally directly by steam-driven turbines. While such systems are suitable for certain applications, they are cumbersome, inefficient and limited by the need for accomodating a steam-driven turbine power source in close proximity to the propeller blades. Furthermore, the propeller speed is directly controlled by the steam turbine thereby adding another source of inefficiency.